1. Field of the Invention
The invention relates to a coupling device of a plug-in coupling with two insertable, tubular coupling parts, i.e., a coupling insert with a peripherally extending securing rib and a coupling receptacle of metal for receiving the coupling insert, for the purpose of connecting two components conveying a fluid, wherein the coupling device is configured as follows: the coupling receptacle has lateral openings and a substantially U-shaped, elastic securing bracket whose legs project through the openings and snap into place behind the securing rib when inserting the coupling parts into one another; at least one sealing ring and a securing bushing in the coupling receptacle facing with one end the sealing ring end resting in the inserted state of the coupling parts on the securing rib.
Moreover, the invention relates to a plug-in coupling with a coupling device according to the invention.
2. Description of the Related Art
In a known coupling device of this type (DE 31 43 015 C3) the embodiment of the coupling receptacle of metal has the advantage that it can be connected more easily, for example, by welding or soldering, with a component of metal conveying the fluid and that the coupling receptacle as well as the component connected thereto ensure a minimal permeation for environmentally damaging fluids, such as fuel or oil, in a motor vehicle. The securing bushing which prevents sliding of the sealing ring (or the sealing rings) in the coupling receptacle extends, however, only between the sealing ring and the circumferential edge of the securing rib. In the inserted or assembled state of the coupling parts this results in a comparatively large radial spacing between the coupling insert and the inner side of the coupling receptacle having the largest diameter at its receiving end. When a radial load acts on the plug-in coupling, for example, as a result of bending of the components in the form of flexible lines connected thereto, be it by the arrangement of the lines or by strong vibrations or impacts, the two coupling parts can be relatively easily deflected relative to one another by a large amount so that there is the risk of leaks of the connection provided by the plug-in coupling, in particular, when the elasticity of the sealing ring, which is usually an O-ring, deteriorates over time. However, this spacing must be selected relatively large so that the legs of the securing bracket, which are guided, respectively, through two, in total thus four, openings in the coupling receptacle and engage with radially outwardly projecting locking noses (beards) behind an edge of two openings, respectively, can be compressed at their free ends for the purpose of decoupling (releasing) so that the locking noses and openings will disengage and the securing bracket can be pulled out of the openings in order to be able to subsequently pull the coupling insert from the coupling receptacle. The legs of the securing bracket in the inserted, coupled state thus may not rest against the circumference of the coupling insert, but must still engage behind the securing rib which means that the securing rib must have a relatively large outer diameter which requires again a correspondingly large inner diameter of the coupling receptacle. The coupling receptacle therefore requires a correspondingly large quantity of material. Moreover, decoupling is difficult because the legs of the securing bracket may be forced (compressed) against one another only to such an extent that the locking noses and the openings will disengage one another without the legs resting fixedly on the circumference of the coupling insert thereby hindering, if not completely preventing, the securing bracket from being pulled out of the openings.
It is an object of the present invention to provide a coupling device of the aforementioned kind and a plug-in coupling provided therewith which in the mounted state ensures a reliable seal-tightness while requiring a minimal material expenditure and makes possible a simpler handling during coupling and decoupling.
In accordance with the present invention, this is achieved in that the coupling receptacle has only two openings positioned diametrically oppositely to one another relative to the coupling receptacle and extending transverse thereto, which openings are in the form of slots, through which one leg of the securing bracket extends in its longitudinal direction, respectively, and in that the securing bushing extends past these slots and is provided with two slots extending transversely to the securing bushing, through which slots the legs of the securing bracket also extend in the longitudinal direction of these slots.
With this embodiment, the legs of the securing bracket can be bent away from one another (can be spread) at the outer side of the coupling receptacle for the purpose of decoupling until they disengage the securing rib. The outer diameter of the securing rib and the inner diameter of the coupling receptacle therefore must not be selected so large that a spacing between the legs and the circumference of the coupling receptacle would remain in the coupled state which would make it possible to compress the legs for the purpose of decoupling. This is made possible by the configuration of the securing bushing with a smaller inner diameter and correspondingly minimal spacing between the securing bushing and the coupling insert so that the outer diameter of the coupling receptacle can also be selected to be smaller and can be produced with less material. Since the securing bushing extends axially past a greater portion of the coupling receptacle, the intermediate space between the coupling receptacle and the coupling insert is filled over a larger axial length by the securing bushing and, accordingly, the spacing between the securing bushing and the coupling insert is smaller across an axially longer area so that the coupling receptacle and coupling insert are deflected to a lesser degree relative to one another when radial loading of the plug-in coupling occurs. The seal-tightness of the plug-in coupling is thus ensured to a greater degree.
Preferably, it is provided that the securing bushing is furnished with a flange projecting past the circumference of the coupling receptacle at its free end. This results, on the one hand, in a reduced spacing between the securing bushing and the coupling insert across an even longer area. On the other hand, the flange substantially prevents in the coupled state an accidental contacting of the securing bracket in the direction of insertion of the coupling insert into the receptacle, for example, during the transport, so that a detachment of the securing bracket in this way is essentially completely prevented. Moreover, the flange, when the securing bracket is removed, provides for a simple removal of the securing bushing by pulling it out of the coupling receptacle in order to exchange the sealing ring or the sealing rings.
A possible configuration resides also in that the flange has two radial cutouts whose bottom has a peripheral section, which is coaxial to the longitudinal center axis of the coupling receptacle and has a greater outer diameter than the coupling receptacle, and further has an adjoining radial depression in the circumferential direction at a wall of the cutout and in that the legs of the securing bracket at their ends have axial projections which project into the cutouts and, in the inserted state of the coupling parts, rest against the coaxial peripheral section and for decoupling can be snapped into place in the depressions by radial movement of the securing bracket. As a result of this configuration, decoupling is possible with a simple radial movement of the securing bracket. When carrying out this movement, the projections of the leg ends glide along the peripheral sections of the cutouts with simultaneous spreading apart of the legs to the point of snapping into place in the depressions so that at the same time the projections come to rest against the wall of the cutout. The spreading apart of the legs disengages them from the securing rib. The coupling insert can thus be pulled out of the coupling receptacle. At the same time, the radial movement is limited by the projections of the leg ends resting on the walls of the cutout so that the securing bracket cannot be pulled radially off the coupling receptacle and be lost.
Also, the cutouts can be closed toward the free end of the securing bushing. The securing bracket is therefore not accessible via the peripheral area of the cutouts in the direction of insertion of the coupling insert into the coupling receptacle.
Moreover, it is possible to provide that the flange in the area opposite the transverse member of the securing bracket has a radial recess. This recess makes it easy to insert a tool such as a screwdriver underneath the transverse member of the securing bracket in order to move it radially for the purpose of decoupling.
The flange can moreover have at least one axial projection which engages a groove in the free end of the coupling receptacle. This ensures that during assembly of the coupling receptacle and the securing bushing a predetermined relative rotational angular position of both parts is maintained in which their slots are aligned with one another, respectively.
Preferably, the securing bushing is comprised of hard plastic material and the securing bracket of a hard-elastic plastic material. This makes possible a fast manufacture of the two parts at large production numbers per time unit.
Moreover, the legs of the securing bracket can have at their facing inner sides a slant widening in the direction of the insertion opening of the securing bushing. This slant facilitates the insertion of the coupling insert into the coupling receptacle up to the point where the securing rib snaps into place behind the legs of the securing bracket.
Moreover, it is advantageous when the coupling insert in a plug-in coupling with the coupling receptacle according to the invention comprises an annular bead which, in the assembled state of the coupling parts, is positioned within the securing bushing at a greater spacing from the sealing ring than the securing rib, so that the legs of the securing bracket engage between the securing rib and the annular bead, wherein the outer diameter of the annular bead is substantially matching the greatest inner diameter of the securing bushing. The coupling insert can then be supported in the case of a radial load of the plug-in coupling by means of the annular bead at the inner side of the securing bushing. This prevents with even greater safety a relative deflection or angled position of the two coupling parts.